A transistor digital computer with a magnetic-drum store

The paper describes the design of a transistor digital computer, the full-scale machine and its prototype. The general arrangement of the two machines is similar, and both employ a magnetic drum for the main and auxiliary stores. The latter are provided by regenerative tracks or revolvers which have reading and writing heads spaced by a distance equivalent to one, two or eight word periods. The output of the reading amplifier is connected via a gate to the writing amplifier, and the track operates as a delay-line type of store. Point-contact transistors are used principally as pulse amplifiers, staticizors and for waveform generation. In the pulse amplifier the transistor operates as a 2-state circuit¿it is turned on by a digit pulse and reset at the end of each digit period by a regular clock waveform with a pulse repetition frequency of 125 kc/s. Point-contact diodes are used to perform the logical operations and for gating. Two-state circuits employing single transistors are also used for the staticizors and for the waveform generation units. A pseudo 2-address code is used in both machines; both the address operand and the address of the next instruction are specified in each instruction, to permit reduction in the access time by optimum coding. The full-scale machine has an 8-word B-register which may also be used as a rapid-access number store and an automatic multiplier.